RAMAN AND TIME-RESOLVED RAMAN STUDIES OF HEME PROTEINS

该计划涉及血红素蛋白的总体长期目标是了解相关多肽与共同血红素基团相互作用以产生这类蛋白质特有的显著功能多样性的分子机制。基本的策略是应用强大的光谱探针，如共振拉曼（RR）和时间分辨拉曼（TR3）的天然和系统操纵的蛋白质，以揭示结构和动态的相互作用，调节血红素的反应性。由于这些蛋白质参与了大量重要的生理过程，包括氧转运和许多类型的氧化代谢途径，因此鉴定负责这种广泛变化的功能的因素对于理解它们在正常和异常状态下的行为将是明显有益的。在这里提出的工作中，一个有效的策略，最近记录的本地血红蛋白四聚体，利用同位素的分子振动的敏感性，被应用到选定的网站修改血红蛋白。新的数据积累，预计将导致更好地了解合作的配体结合的血红蛋白，蛋白质作为一个范例，一般重要的变构过程的分子机制。此外，共振拉曼光谱将用于探测氧化血红素酶如细胞色素P450和哺乳动物过氧化物酶的位点修饰衍生物的活性位点结构，这些蛋白质在许多代谢过程中和防御微生物中是重要的。

The general long-term goal of this program involving heme proteins is to attain an understanding of the molecular mechanisms by which the associated polypeptides interact with a common heme group to produce the remarkable functional diversity which is characteristic of this class of proteins. The essential strategy is to apply powerful spectroscopic probes such as resonance Raman (RR) and time-resolved Raman (TR3) to the native and systematically manipulated proteins in order to reveal the structural and dynamic interactions which regulate heme reactivity. Inasmuch as these proteins are involved in a large number of important physiological processes, including oxygen transport and many types of oxidative metabolic pathways, identification of the factors responsible for this widely varied function would be of obvious benefit for attaining an understanding of their behavior in normal and abnormal states. In the work proposed here an effective strategy recently documented for the native hemoglobin tetramer, which exploits the isotopic sensitivity of molecular vibrations, is being applied to selected site modified hemoglobins. The new data to be accumulated is expected to lead to a better understanding of the molecular mechanism of cooperative ligand binding by hemoglobin, a protein which serves as a paradigm for generally important allosteric processes. In addition, resonance Raman spectroscopy will be used to probe the active site structures of site modified derivatives of oxidative heme enzymes such as cytochromes P450 and mammalian peroxidases, proteins which are important in many metabolic processes and in defense against microorganisms.